What Would Aliens Actually Look Like? We Asked 7 Experts

Movies and TV shows would have us believe aliens would look a bit like us, only with a big (bald) head, green skin, and crazy eyes. But we weren't satisfied with that old cliche. So we decided to ask sci-fi authors, science experts, and ET buffs what they think a real alien might look like.

Kevin Anderson

Kevin Anderson

"Look at the incredible diversity of biotypes here on Earth, all of which evolved under the same planetary environment. I don't believe an alien species from an entirely different biochemical foundation would happen to turn out with two arms, two legs, two eyes, ears, nostrils . . . two genders, warm-blooded, and so on. But, for intelligence one would assume brain capacity, and therefore the body would need some sort of protective mechanism for the vital brain—an exoskeleton, a skull, something like that.

"To build tools they would need some kind of manipulative digits, like fingers (not necessarily an opposable thumb, maybe prehensile tentacles). There would have to be a reproductive system, but it could be budding, seeding, fission, egg laying—not necessarily live, warm-blooded birth. They would require some sort of sensory systems, the analogs of eyes, ears, smelling apparatuses. But their "eyes" would have evolved for the peak spectrum of their own sun, not necessarily ours.

"Do they live in a sea? In the clouds of a gas giant? On land? In a desert? In a jungle? They would need a way to eat or consume energy, and they would need to excrete waste. For intelligence, they'd need to communicate—by voice? Pheromones? Blinking phosphorescent patches?"

Darren Campo

Darren Campo

"When it comes to film and TV, it's problematic to make a race of aliens that does not resemble humans. Actors have to play these roles. What aliens look like in the real world will depend on where they evolved. An alien that evolved in interstellar space would have very different needs from an alien that evolved on an Earthlike planet.

"There is one thing that is nearly certain: an alien life form will be symmetrical. Everything we know of that grows follows a symmetrical pattern. Cut a tree in half lengthwise, the branches and roots on one side would be fairly similar to the other. The same applies to humans and all living growth, even inorganic growth such as crystals and galaxies.

"The size and shape of the alien would be determined by gravity, ambient density, and source of energy. Plantlike aliens are unlikely because photosynthesis doesn't encourage complex survival strategies. The need to chase food favors mobile life. If such life evolved in a thick atmosphere, it's likely to be a horizontal creature. A thinner atmosphere would favor the most vertical animals. Two legs and two arms are more efficient than four legs, so incorporating the rule of symmetry, it's not unlikely that aliens would have evolved just like humans: bipedal and upright.

"When we consider that 95 percent of the universe is not perceptible by our senses or technology (dark matter and energy), then it's most likely that's where the aliens are. So one might say most aliens don't look like anything because they are invisible."